eclipsing binary section

Once you have determined a time of minimum, you can submit it to be published (see Reporting).  However, it can be very fruitful to look at the ToM in the context of an O-C diagram.  This serves two purposes:  it lets you look at how the star is behaving (i.e., is its period constant or changing?), and it provides a sanity check on your ToM.  If your time of minimum really doesn't look right, in terms of previous data, you should revisit all your procedures and look for an error.  Of course, it is completely unacceptable to change a result just because it doesn't fi

Photometry for eclipsing binaries is not different from other stellar photometry.  In fact, as mentioned, most reported ToMs are from untransformed differential data, which simplifies the process.  However, because you might have hundreds of images from one night, all of the same star field, you will appreciate having an automated procedure that does not require picking stars with the computer's mouse on more than a few "starter" images.

EB observing generally involves the following:

The AAVSO has also set up forums, accessible via the main website, to discuss everything from governance to photometry to different types of variable stars.  There is a forum for Eclipsing Binary Stars -- please consider using that as a source for information and place for discussion.

• GCVS query page, for information about a particular variable star.  The home page for the site has links to where you can download the entire GCVS catalogue.  This is useful if you want to filter the database so identify observing targets.
• The AAVSO International Variable Star Index (

The AAVSO does not maintain a current database of times of minima, because there are several other groups already doing so.  Here are links to the most extensive of those resources:

Photometry for eclipsing binaries is not different from other stellar photometry.  In fact, as mentioned, most reported ToMs are from untransformed differential data, which simplifies the process.  However, because you might have hundreds of images from one night, all of the same star field, you will appreciate having an automated procedure that does not require picking stars with the computer's mouse on more than a few "starter" images.